Heating-pressurizing zig for manufacturing 5-layer MEA

ABSTRACT

The present invention provides a heating-pressurizing jig for manufacturing a 5-layer membrane electrode assembly (MEA), in which: metal plates are formed integrally with heating plates to obviate the difficulty in increasing the temperature of the metal plates to a normal state every time when manufacturing a plurality of 5-layer MEAs; an MEA is mounted to external guides while being spaced apart from lower guides at predetermined intervals to prevent the MEA from being dried, contracted and deformed by the heated metal plates; and the lower guides and upper plate supports are elastically supported by springs, respectively, so that the external guides can respond in real time to the change in the thickness caused when upper and lower gas diffusion layers are compressed, thus preventing the MEA from being bent.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. §119(a) on Korean PatentApplication No. 10-2007-0098651, filed on Oct. 1, 2007, the entirecontents of which are incorporated herein by reference.

BACKGROUND

(a) Technical Field

The present invention relates to a heating-pressurizing jig formanufacturing a 5-layer membrane electrode assembly (MEA). Moreparticularly, the present invention relates to a heating-pressurizingjig for manufacturing a 5-layer MEA, in which external guides areprovided to separate an MEA from heating plates, metal plates areintegrally connected to the heating plates to preserve the temperatureof the metal plates for a predetermined period of time, and a springstructure is provided to actively adjust the position of the externalguides according to the thickness of a gas diffusion layer.

(b) Background Art

A fuel cell includes an MEA consisting of electrode catalysts in whichfuel gasses such as hydrogen and air react and an electrolyte membranefor transporting hydrogen ions in a fuel cell.

The fuel cell also includes a gas diffusion layer (GDL) to uniformlydiffuse the gas supplied through a separator flow field and effectivelydischarge water generated as a result of an electrochemical reaction.

The MEA, GDL and separator are sequentially stacked to constitute a fuelcell stack. In this case, if the MEA and GDL are modularized, theproductivity of the fuel cell stack can be increased.

A 5-layer MEA and a method for manufacturing the same will be describedwith reference to accompanying drawings below.

FIG. 1 is a schematic diagram of a 5-layer MEA, and FIGS. 2A and 2B arediagrams illustrating positional relationship between a gas diffusionlayer and electrode catalysts of the 5-layer MEA of FIG. 1.

Usually, an MEA 130 composed of a hydrogen electrode catalyst 110, asolid electrolyte membrane 100 and an air electrode catalyst 120 iscalled a 3-layer. A GDL 140 is attached to both sides of the MEA 130.For convenience of manufacturing, one MEA 130 and two GDLs 140 arebonded to manufacture a final product, which is called a 5-layer MEA 90.

In order to manufacture the 5-layer MEA 90, the components aresequentially stacked, aligned and then bonded by applying pressure at apredetermined temperature for a predetermined period of time.

The temperature and pressure vary according to product characteristicsand various kinds of additives are added thereto for the purpose ofbonding the components, if necessary.

In manufacturing the 5-layer MEA 90, a hot press the temperature andpressure of which are adjustable and a jig that can place the componentsat an accurate position are needed.

Normally, the GDL 140, the MEA 130 and the GDL 140 are sequentiallystacked and a uniform pressure is applied to both the GDLs 140 usingheated hot plates.

Here, as shown in FIG. 2A, one of the important things to be consideredin manufacturing the 5-layer MEA 90 is that both GDLs 140 shouldcompletely cover the electrode catalysts 110 and 120 of the MEA 130 andthe positions of both the GDLs 140 should accurately coincide with eachother.

As shown in FIG. 2B, if the GDL 140 does not completely cover theelectrode catalysts 110 and 120, gas cannot be sufficiently supplied tothe catalysts, thus degrading the performance of the fuel cell.Moreover, if the GDL 140 comes out of the separator, it is impossible tomanufacture the fuel cell.

Furthermore, if the positions of both the GDLs 140 do not coincide witheach other, a force imbalance is created in manufacturing the fuel cell,thus degrading the performance of the fuel cell.

In connection with such a heating-pressurizing jig, Japanese PatentApplication Publication No. 2000-208140 discloses a lamination deviceincluding heating type compression main bodies arranged in parallel,between which electrode members are inserted to be heated andcompressed.

Moreover, U.S. Pat. No. 6,613,470 discloses a jig that pre-heats andpre-pressurizes components to be temporarily fixed before manufacturingan MEA by an overall heating-pressurizing process.

The conventional heating-pressurizing jig for manufacturing a 5-layerMEA will be described in detail below with reference to FIG. 3.

FIG. 3 is a schematic diagram of the conventional heating-pressurizingjig for manufacturing a 5-layer MEA. As shown in the figure, a lowermetal plate 160 is disposed between main bodies 150, a lower GDL 170 isplaced on the top of the lower metal plate 160, and an MEA 130 isstacked on the top of the lower GDL 170.

A GDL guide 190 is mounted on both sides of the MEA 130, an upper GDL200 is placed thereon, and an upper metal plate is covered thereon.Then, predetermined temperature and pressure are applied using a hotpress, not depicted, thereto to form a 5-layer MEA.

In this case, since hot plates, not depicted, of the hot press arespaced away from the upper and lower metal plates 160 and 210, it isdifficult to maintain the temperature and it takes a lot of time toincrease the temperature of the upper and lower metal plates 160 and 210to a desired level.

Moreover, since the polymer MEA 130 is placed on the heated lower metalplate 160, the MEA 130 may be wrinkled due to moisture evaporation, thusdegrading the bonding strength, MEA properties, and dimensionalstability.

In addition, during the pressurizing process by the jig, both sides ofthe MEA 130 coming in contact with the ends of the upper and lower GDLs200 and 170 may be bent while the upper and lower GDLs 200 and 170 arecompressed, thus being damaged.

The information disclosed in this Background section is only forenhancement of understanding of the background of the invention andshould not be taken as an acknowledgement or any form of suggestion thatthis information forms the prior art that is already known to a personskilled in the art.

SUMMARY OF THE DISCLOSURE

Accordingly, the present invention has been made in an effort to solvethe above-described drawbacks, and one of the objects of the presentinvention is to provide a heating-pressurizing jig for manufacturing a5-layer MEA with an improved structure to effectively manufacture the5-layer MEA.

In one aspect, the present invention provides a heating-pressurizing jigfor manufacturing a 5-layer membrane electrode assembly, the jigcomprising: a lower metal plate, a lower guide, a guide spring, anexternal guide, an upper metal plate, and an upper plate support. Thelower metal plate is installed on the top surface of a lower heatingplate. On the lower metal plate, a lower gas diffusion layer is stacked.The lower guide is installed on both sides of the lower metal plate toguide the lower gas diffusion layer to a predetermined positionaccurately. The guide spring is installed below the lower guide toelastically support the lower guide. The external guide is mounted onthe top of the lower guide to fix a membrane electrode assembly and anupper gas diffusion layer. The upper metal plate is mounted on thebottom surface of an upper heating plate. The upper metal platepressurizes the upper gas diffusion layer when a press is moved down.The upper plate support is installed on both sides of the upper metalplate. The upper plate support comes in contact with the external guidewhen the press is moved down.

In a preferred embodiment, the upper plate support is elasticallysupported by an upper plate spring.

In another preferred embodiment, an insulating material is disposedbetween the guide spring and the lower heating plate.

In still another preferred embodiment, a projection is formed on thebottom of the external guide and an insertion groove corresponding tothe projection is formed on the top of the lower guide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a 5-layer MEA;

FIGS. 2A and 2B are diagrams illustrating positional relationshipbetween a gas diffusion layer and electrode catalysts of the 5-layer MEAof FIG. 1;

FIG. 3 is a schematic diagram of a conventional heating-pressurizing jigfor manufacturing a 5-layer MEA;

FIG. 4 is a schematic diagram of a heating-pressurizing jig formanufacturing a 5-layer MEA in accordance with a preferred embodiment ofthe present invention; and

FIG. 5 is an operational diagram of the heating-pressurizing jig formanufacturing a 5-layer MEA in accordance with a preferred embodiment ofthe present invention.

Reference numerals set forth in the Drawings includes reference to thefollowing elements as further discussed below:

130: MEA 200: GDL 210: lower metal plate 220: guide spring 230: lowerguide 260: insulating material 270: external guide 300: upper metalplate

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiment of thepresent invention, examples of which are illustrated in the drawingsattached hereinafter, wherein like reference numerals refer to likeelements throughout. The embodiments are described below so as toexplain the present invention by referring to the figures.

FIG. 4 is a schematic diagram of a heating-pressurizing jig formanufacturing a 5-layer MEA in accordance with a preferred embodiment ofthe present invention.

As shown in the figure, a lower guide 230 supported by a guide spring220 is installed on both sides of a lower metal plate 210 on which alower gas diffusion layer (GDL) 170 is stacked. An external guide 270for fixing a membrane electrode assembly (MEA) 130 and an upper GDL 200is provided on the top of the lower guide 230. Moreover, an upper platesupport 310 and an upper metal plate 300 which pressurize the externalguide 270 and the upper GDL 200, respectively, when a press 360 is moveddown are provided on the top of the external guide 270.

The lower metal plate 210 is formed integrally with the top of a lowerheating plate 250 to transfer heat generated from the lower heatingplate 250 to the lower GDL 170 stacked on the top of the lower metalplate 210.

The lower guide 230 is mounted closely to both sides of the lower metalplate 210 to guide the lower GDL 170 so as to be accurately positionedwhen the lower GDL 170 is stacked on the top surface of the lower metalplate 210.

In this case, the distance between both the lower guides 230 is equal tothe length of the lower GDL 170 and the height of the lower guides 230is greater than that of the lower metal plate 210 such that the lowerGDL 170 is disposed between both the lower guides 230.

Moreover, the guide spring 220 is mounted below the lower guide 230 suchthat the lower guide 230 contracts when the upper metal plate 300 andthe upper plate support 310 are pressurized. A guide support 240 isprovided next to the lower guide 230 so that the lower guide 230 is notpushed to the outside when the lower guide 230 contracts.

Here, an insulating material 260 is stacked on the bottom of the guidespring 220 and the guide support 240 so that the heat of the lowerheating plate 250 is not directly transferred to the guide spring 220and the guide support 240.

The external guide 270 is mounted on the top of both the lower guides230 and includes an insertion portion 271 for guiding the MEA 130 and aguide portion 272 mounted on the top surface of the insertion portion271 to guide the upper GDL 200.

In this case, the distance between the insertion portions 271 is equalto the length of the MEA 130 and the distance between the guide portions272 is equal to the length of the upper and lower GDLs 200 and 170.

Moreover, a projection 280 is formed on the bottom of the external guide270 and an insertion groove 290 corresponding to the projection 280 isformed on the top of the lower guide 230 so that the external guide 270is mounted at an accurate position of the lower guide 230, and therebythe lower GDL 170 can completely cover the electrode catalyst of the MEA130.

Like this, the MEA 130 and the upper GDL 200 are separately mounted tothe external guides 270 so that they are spaced apart from the lowermetal plate 210 before the operation of the press 360, thus preventingthe MEA 130 from being dried and deformed by the heated lower metalplate 210.

The upper metal plate 300 is mounted in the center of the bottom of anupper heating plate 340 and moved down during the operation of the press360, thus pressurizing the MEA 130, mounted to the external guides 270,and the lower GDL 170.

Here, the sizes of the upper and lower metal plates 300 and 210 are thesame as those of the upper and lower GDLs 200 and 170 so that thepressure of the upper and lower metal plates 300 and 210 is uniformedapplied to the overall surface of the upper and lower GDLs 200 and 170.

Moreover, a fixing body 330 having an internal space 350 is mounted onboth sides of the upper metal plate 300 and a portion of the upper platesupport 310 is inserted and mounted in the internal space 350 of thefixing body 330 such that the upper plate support 310 can move up anddown.

Here, an upper plate spring 320 is disposed between the upper platesupport 310 and the fixing body 330 to elastically support the upperplate support 310 when the upper plate support 310 pressurizes theexternal guide 270.

Next, the operation of the heating-pressurizing jig for manufacturing a5-layer MEA having the above configuration will be described withreference to FIG. 5.

FIG. 5 is an operational diagram of the heating-pressurizing jig formanufacturing a 5-layer MEA in accordance with a preferred embodiment ofthe present invention.

First, the lower GDL 170 is mounted on the top surface of the lowermetal plate 210 and the external guides 270 on which the MEA 130 and theupper GDL 200 are stacked are installed to coincide with the insertiongrooves 290 of the lower guides 230.

Subsequently, as shown in FIG. 5, the upper heating plate 340 is moveddown by the operation of the press 360 according to the pressure of aload cell 370 installed on the top of the press 360, and thus the upperplate supports 310 mounted on the bottom of the upper heating plate 340pressurize the external guides 270.

Next, as the upper heating plate 340 is further moved down, the guidesprings 220 elastically supporting the lower guides 230 are contractedsuch that the MEA 130 comes in contact with the lower GDL 170. Then, asthe upper plate springs 320 elastically supporting the upper platesupports 310 are contracted, the upper metal plate 300 comes in contactwith the upper GDL 200.

At this time, with the change in the thickness caused when the upper andlower GDLs 200 and 170 are compressed, the external guides 270 are movedby the contraction and relaxation of the guide springs 220 and the upperplate springs 320, and thus the MEA 130 inserted into the externalguides 270 can be prevented from being bent.

Consequently, a 5-layer MEA in which the upper GDL 200, the MEA 130 andthe lower GDL are sequentially stacked is formed when the respectivelayers are heated and pressurized for a predetermined period of time bythe upper and lower metal plates 300 and 210 supplied with heat from theupper and lower heating plates 340 and 250.

As described above, the heating-pressurizing jig for manufacturing a5-layer MEA in accordance with the present invention provides thefollowing advantageous effects:

(1) Since the metal plates are formed integrally with the heatingplates, the difficulty in increasing the temperature of the metal platesto a normal state every time when manufacturing a plurality of 5-layerMEAs is reduced;

(2) Since the MEA is mounted to the external guides while being spacedapart from the lower guides at predetermined intervals, it is possibleto prevent the MEA from being dried, contracted and deformed by theheated metal plates;

(3) Since the lower guides and the upper plate supports are elasticallysupported by the springs, respectively, the external guides can activelycope with the change in the thickness in real time caused when the upperand lower GDLs are compressed, thus preventing the MEA from being bent;and

(4) When the sizes of the MEA and GDL are changed according to thedevelopment of a new vehicle model, it is possible to replace only thejig newly designed and manufactured, thus manufacturing the 5-layer MEAsat low cost without the replacement of the press.

The invention has been described in detail with reference to preferredembodiments thereof. However, it will be appreciated by those skilled inthe art that changes may be made in these embodiments without departingfrom the principles and spirit of the invention, the scope of which isdefined in the appended claims and their equivalents.

1. A heating-pressurizing jig for manufacturing a 5-layer membraneelectrode assembly, the jig comprising: a lower metal plate installed onthe top surface of a lower heating plate, on which a lower gas diffusionlayer is stacked; a lower guide installed on both sides of the lowermetal plate to guide the lower gas diffusion layer to a predeterminedposition accurately; a guide spring installed below the lower guide toelastically support the lower guide; an external guide mounted on thetop of the lower guide to fix a membrane electrode assembly and an uppergas diffusion layer; an upper metal plate mounted on the bottom surfaceof an upper heating plate, which pressurizes the upper gas diffusionlayer when a press is moved down; and an upper plate support installedon both sides of the upper metal plate, which comes in contact with theexternal guide when the press is moved down.
 2. The heating-pressurizingjig for manufacturing a 5-layer membrane electrode assembly of claim 1,wherein the upper plate support is elastically supported by an upperplate spring.
 3. The heating-pressurizing jig for manufacturing a5-layer membrane electrode assembly of claim 1, wherein an insulatingmaterial is disposed between the guide spring and the lower heatingplate.
 4. The heating-pressurizing jig for manufacturing a 5-layermembrane electrode assembly of claim 1, wherein a projection is formedon the bottom of the external guide and an insertion groovecorresponding to the projection is formed on the top of the lower guide.